title: Characterization of D-galacturonate reductase purified from the psychrophilic yeast species Cryptococcus diffluens.
abstract: D-Galacturonic acid reductase was purified from a psychrophilic yeast strain of Cryptococcus diffluens, which was isolated from Satho, a traditional alcohol drink in Thailand. This enzyme, named Cd-GalUAR, assimilates D-galacturonic acid and requires NADPH as a cofactor. Cd-GalUAR is about 45 kDa and stable from pH 6.5 to 7.5 and up to 35°C. Its optimum pH and temperature are pH 7.0 and 40°C, respectively. However, 80% of its maximum activity remained at 4°C. The reaction of Cd-GalUAR from D-galacturonic acid produces L-galactonic acid, which was identified by (13)C NMR and LC-MS. Three amino acid sequences were determined from trypsin-digested peptides of Cd-GalUAR. Similar sequences are found in many NAD or NADP oxidoreductases, including some D-galacturonate reductases. Our results suggest that Cd-GalUAR is the first D-galacturonate reductase identified in yeast.
authors.affiliation: Division of Applied Life Science, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai, Osaka, Japan.
authors.forename: Shohei
authors.initials: S
authors.lastname: Hamada
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Seike
authors.forename: Shinji
authors.initials: S
authors.lastname: Tanimori
authors.forename: Tatsuji
authors.initials: T
authors.lastname: Sakamoto
authors.forename: Masao
authors.initials: M
authors.lastname: Kishida
mesh_terms: D000429:Alcohol Oxidoreductases / Q000302:isolation & purification / Q000378:metabolism*; D000434:Alcoholic Beverages / Q000382:microbiology; D003001:Cloning, Molecular; D003454:Cryptococcus / Q000201:enzymology*; D005656:Fungal Proteins / Q000302:isolation & purification / Q000378:metabolism*; D006603:Hexuronic Acids / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D064430:NAD (+) and NADP (+) Dependent Alcohol Oxidoreductases; D009249:NADP / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D020539:Sequence Analysis, Protein; D013379:Substrate Specificity; D013400:Sugar Acids / Q000378:metabolism; D013696:Temperature; D013785:Thailand
chemical_list: D005656:Fungal Proteins; D006603:Hexuronic Acids; D013400:Sugar Acids; C012991:galactonic acid; C007819:galacturonic acid; D009249:NADP; D000429:Alcohol Oxidoreductases; D064430:NAD (+) and NADP (+) Dependent Alcohol Oxidoreductases; C477073:D-galacturonate reductase